* [patch 1/2]cfq-iosched: fix a rcu warning
@ 2011-06-27 6:52 Shaohua Li
0 siblings, 0 replies; only message in thread
From: Shaohua Li @ 2011-06-27 6:52 UTC (permalink / raw)
To: lkml; +Cc: Jens Axboe
I got a rcu warnning at boot. the ioc->ioc_data is rcu_deferenced, but
doesn't hold rcu_read_lock.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index f379943..fd566c1 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2773,11 +2773,14 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
smp_wmb();
cic->key = cfqd_dead_key(cfqd);
+ rcu_read_lock();
if (rcu_dereference(ioc->ioc_data) == cic) {
+ rcu_read_unlock();
spin_lock(&ioc->lock);
rcu_assign_pointer(ioc->ioc_data, NULL);
spin_unlock(&ioc->lock);
- }
+ } else
+ rcu_read_unlock();
if (cic->cfqq[BLK_RW_ASYNC]) {
cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
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